Punch



Patented Mar. 24, 1931 UNITED STATES PATENT OFFICE FLOYD C. KING, 0FBIRMINGHAM, MICHIGAN, ASSIGNOR T0 GUARDIAN TRUST COM- PANY, OF DETROIT,MICHIGAN, A CORPORATION 0F MICHIGAN, TRUSTEE PUNCH Application led June10, 1929. Serial No. 369,905.

This invention relates generally to punches and refers more particularlyto the type of.

punch set forth in my applicationfiled February 11, 1929, bearing SerialNo. 339,145.

One of the essential objects of the invention is to provide a punch thatwill be effectively held in, but may be easily and quickly released froma holder such as that set forth in the application above mentioned.

the invention consists of certain novel features of construction thatwill be hereinafter more fully described and particularly pointed outinthe appended claims.

In the accompanying drawing: Figure 1 is a vertical sectional Viewthrough a retainer and showing a punch embodying my invention inoperative position in said retainer;

Figure 2 is a detail view of the punch; Figure 3 is a sectionalvieWt-aken on the line 3-3 of Figure 2.

Referring now to the drawings, 1 is a punch having suitable shank andWork engaging head portions, 2 and 3 respectively, 4 is a retainer bodyhaving a bore 5 for receiving the shank 2 of the punch and having apocket or recess 6 at one side ofthe bore containing means for retainingthe'shank 2 in the bore 5. As shown the means in the recess 6 in theholder 4 for retaining the punch shank 2 in the bore 5 comprises a levery 14' having a rounded or spherical end portion 15 pivotally engaging arounded portion 16 of the recess 6 and preferably having an arcuate endportion 17 engageable With the longitudinally curved base 18 of anarcuate recess 19 in one side of the punch shank 2, a coil spring 20engaging the lever 14 and normally holding the arcuate end portion 17thereof in the bore 5, and a shell 21 that constitutes a housing for thespring 2O and for the spherical end portion 15 of the lever and thatprevents accidental displacement of the said spherical portion 15 yfrom-the rounded portion 16 of the recess 6.

The rounded portion 16 of the recess 6 is concentric with the center 22of the spherical portion 15 and constitutesv a hacker or bearing forsaid spherical portion in all positions of pivotal adjustment of thelever. In fact, the arrangement of the spherical end rounded portions 15and 16 respectively is such that the spherical portion 15 slidablyengages the rounded portion 16, and the outer free end of With the aboveandother objects in View;

the lever is so fashioned With respect to the base 18 of the recess 19in the punch that the longitudinal thrust imparted to the lever when thefree end thereof is engaged With the base 18 of said recess istransmitted directly from the spherical portion 15 to the roundedportion 16.. Therefore, as the lever swings in an arc the sphericalportion! 15 Will transmit this thrust or load to correspondingly dierentpoints of the rounded portion 16. Moreover, due to this arrangement ofthe spherical androunded portions, the outer free end of the lever maybe so fashioned that the punch will be effectively held by the leveracting as a prop or brace and may be easily and quickly released fromthe lever and removed from thev body 4 as Will be hereinafter more fullyset forth. p

Preferably the arcuate endl portion 17 of the lever is eccentric to thecenter 22, said arcuate end portion 17 being concentric with aneccentric point 22 of the spherical portion 15. Moreover, When the partsare in the position illustrated in Figure 1, the longitudinally curvedbase 18 of the recess 19 in the shank 2 is also eccentric to the center22, but concentric with the arcuate end portion 17, the dotted line inFigure 1 representing an arc concentric With the center 22. As shown therecess 19 is adjacent to the upper end of the shank 5, hence when thearcuate end portion 17 engages Vthe base 18 of the recess in the toolshank 2, a propping or bracing action in contradistinction to a Wedgingaction, and an area contact instead of a point contact is obtained.Likewise when the lever is'raised the end portion 17 is released fromthe base 18 and is therefore readily re- 17 of the lever willautomatically engage the` base 18 of the recess 19 in the shank 2 andposition. However, any suitable means such as the shank. 50 of a. tool51 may be inserted through a bore 25 into the recess 6 to disengage thelever 14 from the shank .2.

readily removed from a holder without the necessity of taking apart theholder or separating it from the usual backing plate 40. Moreover, abetter gripping action is obtained 20 and there is no tendency of theparts to wedge.

In the preferred embodimentof my invention, the recess 19 in the shank 2is transverselv curved in arcuate form as indicated at 18A. The recessmay be described as having a surface formed bv the intersection of atore with the cylindrical shank 2. In the preferred construction thetore defining the curvature of the recess has anvoutside diameter'substantiallv three times the diameter of the generating circle whichdefines the transverse curvature. The depth of the recess is preferablv1/3 of the diameter of the generating circle.

It is desirable that the recess 19 be main-I tained cuite accuratelywithin certain limits of tolerance Aand one specific construction thathas proved to have exceptional merit has a generating circlecorresponding to the following formula:

In this Ycase the depth of the recess corresponds to the followingformula:

MA=.333 MC- .0104i .010

In the above formulas MA represents the depth of the recess, MC thediameter of the generating circle and MB the outside diameter of thetore. 5 What I claim as my invention is:

1. A punch having a longitudinally extending groove, theJ surface ofsaid groove corresponding to a" tore in which the gengroove having adepth approximately 1/3 of the diameter of the generating circle of saidtore.

2. A punch having a longitudinally extending groove arcuately curvedboth longitudinally and transversely, the diameter of the transversecurvature being substantially U5 and the depth ofthe groove beingsubstanwill effectively hold the punch in assembledL Thus, withmvconstruction a tool may be erating circle is substantially l the diame-1,45 the diameter of the longitudinal curvature tially 1/3 the diameterof the transverse arcuate curve.

3. A punch having a longitudinally extending groove having a sur acesuch as is formed by the intersection of a cylinder with a tore in whichthe tore has a generating circle substantially equal to 1%; of theoutside diameter of the tore minus 315 of an inch, said groove having adepth-approximatel 1/3 -the iameter of the generating circle o saldtore.

In testimony whereof I aiiix my signature.

FLOYD C. KING.

